|
Directory Identifier: GRAVCD-sandwell
Contributing Organization: Scripps Institution
of Oceanography
Summary: The high density Geosat/GM altimeter data south of 30 S have finally arrived. In addition, ERS-1 has completed more than 6 cycles of its 35-day repeat track. These data provide a dramatically improved view of the marine gravity field. Additional information is available. The files in this directory contain global marine gravity anomalies gridded on a Mercator projection (see Sandwell and Smith, EOS trans. AGU, v. 73, p. 133, Fall 1992 AGU meeting supplement). The grid was derived from the following data sources: Seasat Used in areas north of 30 S latitude. Profiles within 10 km of a Geosat/ERM track were excluded. Geosat/ERM Average of 62 Geosat Exact Repeat Mission profiles. Geosat/GM Recently declassified Geosat Geodetic mission data south of 30 S. ERS-1 Fast delivery IGDR's obtained from Bob Cheney at NOAA. Six, 35-day repeat cycles were used in the grid. All of these data were gridded using the method described in: Sandwell, D. T., Antarctic marine gravity field from high-density satellite altimetry, Geophys. J. Int., v. 109, p. 437-448, 1992. The method was adapted to accommodate multiple satellite inclinations (Sandwell, D. T., A detailed view of the South Pacific from satellite altimetry, J. Geophys. Res., v. 89, p. 1089-1104, 1984). The gridded data are stored in an 2-byte integer format without any header or record information. world_grav.image A 4224 by 7800 grid of 2-byte integers = 65894400 bytes. The gravity anomaly units are 0.1 milligal. The Mercator projected image spans longitudes from 0 E to 390 E and latitudes from 72.006 N to -72.006 N. The center of the upper left grid cell (i.e. the first integer in the file) is located at 71.998 N, .025 E. Longitudes increase with a 1/20 degree spacing. The center of the last integer in the file is located at - 71.997 N, 389.975 E.CAVEAT: The preceding description was provided to NGDC with the original data contribution. It has been kept in this format to preserve the sense of data lineage. The formats described may not exactly match those on the CD-ROM, which are documented consistently within “.FMT”, “.HDR” and “.GRD” files.
Return to the Top of this Document Return to the Gridded Data Set Table Return to Gravity 1999 |
 |
|
| All MGG Data | All Marine Geophysics | Bathymetry | Seismic Reflection | Trackline Geophysical Data Viewer |